bright adj.

*bherəg-, Proto-Indo-European root meaning "to shine; bright, white." It forms all or part of: Albert; Bertha; birch; bright; Egbert; Ethelbert; Gilbert; Herbert; Hubert; Lambert; Robert.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit bhrajate "shines, glitters;" Lithuanian brėkšti "to dawn;" Welsh berth "bright, beautiful."

masc. proper name, from an Old North French form of Old High German Hrodberht "bright-fame, bright with glory," from hrod- "fame, glory" (from Proto-Germanic *hrothi-), + *berht "bright" (from PIE root *bhereg- "to shine; bright, white"). Never a king's name, though it was the name of William the Conqueror's rebellious oldest son. "It was introduced by Normans during the reign of Edward the Confessor and became very popular" ["Dictionary of English Surnames"].

In Middle English, from mid-13c., also "a designation for a robber, vagabond, or lowly person" ["Middle English Compendium"]; hence Robertes men "robbers, marauders;" Robert-renne-aboute "a wastrel, a good-for-nothing."